Boosting rice yields generates optimism

Early research on improving photosynthesis in rice plants is giving investigators reason for optimism, Cambridge University plant scientist Julian Hibberd told the International Association for Plant Biotechnology (IAPB) 12th World Congress.

Hibberd’s work on the C4 Rice Project is searching for ways to genetically modify rice plants, which use C3 photosynthesis, to the more productive C4 form found in plants such as maize and sorghum. He is part of a project coordinated by the International Rice Research Institute and funded by an $11 million grant from the Bill and Melinda Gates Foundation.

The goal is to increase by 50 percent the yield of rice, which about half of the world’s population depends on as a staple. Because rice feeds more people than any other crop and yields have started to plateau worldwide, Hibberd said, increasing production is critical to food security,

“The challenge is absolutely huge, but we should be able to understand the mechanisms underlying C4 photosynthesis with enough time and money devoted to it,” Hibberd told members of the Congress, attended by about 800 scientists, science policy leaders and others from more than 50 countries around the world.

Members of the C4 rice project have started to identify mutant lines of rice that show alterations in leaf structure that could help rice to be modified into a C4 plant.

“The C4 pathway is extremely complicated, so engineering it into a crop like rice is a massive challenge,” Hibberd said. “But it has evolved many times independently, so that’s one reason for optimism. We also know there are a large number of enzymes that are recruited in the C4 pathways, but they are all present in plants that use the C3 pathway.”

Part of the difficulty of engineering C4 rice is understanding and controlling the interaction between changes in the rice leaf’s structure, biochemistry and cell biology. The leaf structure is an area with the least amount of research and on which the C4 Rice Project is intended to have an impact.

“We have to manipulate all three,” Hibberd said. “We are probably still at least 15 years away from seed production, but the fact that it has evolved many times alongside some promising initial results from the C4 rice project provide cause for optimism.”

This presentation was one of 60 major presentations by invited speakers and more than 200 short talks. Presenters discussed biotechnology in terms of agriculture challenges as a result of climate change and global population growth. More information is available online at www.iapb2010.org.